Common Grammar Errors

Explanations and examples of the most common grammar errors in English

The categories listed below give a very general overview of the kinds of errors often made by speakers of English, whether native speakers or those studying English as a foreign language. I have provided a very basic explanation of each type of error, along with a convenient acronym for it, a sentence containing a specific example of the error, and a corrected version of the same sentence. I have also included links to more detailed discussions of many of these topics. As I expand this website further I will add additional links.

If you learn how to consistently identify and correct all of these kinds of errors, you will have a solid foundation in the skills necessary for effective writing, and you will be well prepared for standardized tests such as the SAT and ACT.

This list does not include errors in mechanics such as capitalization and punctuation errors.

A PDF version of this page can be downloaded here.

Subject-Verb Agreement

Singular subjects require singular verb forms; plural subjects require plural verb forms. An error in subject-verb agreement (SVA) occurs when the number of the subject and the number of its verb do not match:

Michael K. Williams play the role of Omar in The Wire.

Michael K. Williams plays the role of Omar in The Wire.

The subject Michael K. Williams is singular, so it requires the singular verb form plays.

There is thirteen provinces and territories in Canada.

There are thirteen provinces and territories in Canada.

The compound subject provinces and territories is plural, so it requires the plural verb form are.

See my Subject-Verb Agreement page for more information.

Grammar Navigation Menu

Parts of Speech: Word classes; different kinds of words (nouns, verbs, etc.)

Sentence Analysis: A system for identifying the main elements of a sentence (subjects, verbs, phrases, clauses) and how they relate to each other

Subject-Verb Agreement: Rules about consistency of number (singular or plural) between subjects and their verbs

Parallelism: Rules about how to maintain consistent form in lists and other parallel structures

Usage: Conventions about how specific words and phrases are used

Punctuation: The use of punctuation marks to clarify relationships among words in a sentence

Exercises & Quizzes: Exercises and quizzes to practice and test your understanding of the rules of English grammar

Number Agreement: Nouns and Pronouns

Noun number agreement and pronoun number agreement are similar to subject-verb agreement in that they both involve different words in a sentence agreeing in number (i.e., singular or plural).

An error in noun number agreement (NNA) occurs when two nouns in a sentence that refer to the same thing are different in number:

Tim and Tony wanted to be an NBA player.

Tim and Tony wanted to be NBA players.

Since NBA player refers to or renames two people, Tim and Tony, it must be plural in form instead of singular.

An error in pronoun number agreement (PNA) occurs when a plural pronoun is used to refer to a singular antecedent (the noun or pronoun it stands for), or when a singular pronoun is used to refer to a plural antecedent:

The team made a great decision when they chose Manu Ginobili with the 57th pick in the NBA draft.

The team made a great decision when it chose Manu Ginobili with the 57th pick in the NBA draft.

The antecedent team is singular, so the singular pronoun it (which takes the place of team) should be used instead of the plural pronoun they. (Note that in informal English, the use of plural pronouns in situations like this is very common and generally accepted.)

See my Pronouns page for more information.

Pronoun Case

Pronoun cases are different forms of a pronoun that are used in different grammatical roles in a sentence. Nominative case pronouns, also called subject pronouns, are used when the pronoun is acting as a subject or a predicate nominativeObjective case pronouns, also called object pronouns, are used when the pronoun is acting as the object of a verb or object of a preposition. An error in pronoun case (PC) occurs when an object pronoun is used instead of a subject pronoun, or vice versa:

Between you and I, Superman’s costume is pretty lame compared to Batman’s.

Between you and me, Superman’s costume is pretty lame compared to Batman’s.

Since the pronoun I functions as an object of the preposition between, it should be replaced with the objective case pronoun me.

Possessive pronouns are also referred to as genitive case pronouns, so errors involving possessive pronouns can also be classified as pronoun case errors.

See my Pronouns page for more information.

Pronoun Reference

Most pronouns must have a clear antecedent; that is, it should be easy to tell what specific person, place, thing, or idea a pronoun refers to. Errors in pronoun reference (PR) occur when a pronoun does not have a clear antecedent, resulting in an ambiguous pronoun or a vague pronoun:

Strider told Pippin that he couldn’t have second breakfast or elevenses.

Strider told Pippin that Pippin couldn’t have second breakfast or elevenses.
Strider told Pippin that they didn’t have time for second breakfast or elevenses.
Strider told Pippin not to stop for second breakfast or elevenses.

In the original sentence, the pronoun he could refer to Aragorn or to Pippin (it is possible that Aragorn is talking about himself), so it is ambiguous, and the meaning of the sentence is unclear. This problem can be corrected by repeating the antecedent Pippin instead of using a pronoun or by rewording the sentence to avoid the confusing pronoun.

See my Pronouns page for more information.

Pronoun Shift

Pronoun use within a sentence or paragraph should be consistent. Switching from one pronoun to another to refer to the same antecedent is called pronoun shift (PS), and it can cause confusion about what you’re referring to:

One should never taunt a superhero, but you should especially avoid joking about Thor’s beer belly.

One should never taunt a superhero, but one should especially avoid joking about Thor’s beer belly.
You should never taunt a superhero, but you should especially avoid joking about Thor’s beer belly.

In the original sentence, one and you both refer to the same thing (an indefinite, generalized person), but switching from one pronoun to the other for no reason may cause confusion. Either one (more formal) or you (more informal) can be used in this context, but not both.

See my Pronouns page for more information.

Parallelism

In grammatical terms, parallelism is the use of consistent form in different parts of a sentence. (In a broader sense, parallelism is also a stylistic or rhetorical technique that can be used to express an idea more clearly or memorably.) Errors in parallelism (P) occur when a sentence element that requires consistent form (such as a list, comparison, or either/or structure) does not follow the same pattern throughout the element:

In the game Minecraft, players must learn how to gather resources, how to build a shelter, how to fight monsters, and also crafting useful items.

In the game Minecraft, players must learn how to gather resources, build a shelter, fight monsters, and craft useful items.

The list in the first sentence above starts off with the infinitives to gather and to build, but the last item in the list is the gerund crafting. To follow the principle of parallelism, you must use the same form for all items in the list. With parallel structures, you can also use very concise wording; in this case, “how to” only needs to be written once since it is understood to apply to each item in the list.

See my Parallelism and Faulty Comparisons page for more information.

Comparison

In standard English, comparisons should be worded carefully so that they are strictly logical and parallel. A faulty comparison (FC) occurs when they are either not logical or not parallel. Avoid “apples and oranges” comparisons involving two fundamentally different things that aren’t actually the two things you intend to compare:

Surprisingly, our cat Katana seems to like Metallica’s music more than Beethoven.

Surprisingly, our cat Katana seems to like Metallica’s music more than Beethoven’s.

The first sentence above compares Metallica’s music, an abstract thing, to Beethoven, a person. Clearly, the intended meaning of the sentence is a comparison between Metallica’s music and Beethoven’s music, so the comparison should be reworded to make it parallel. (Note that the parallel structure of the comparison allows you to omit the word music from the second part, since it is understood.)

See my Parallelism and Faulty Comparisons page for more information.

Comparative and Superlative Forms

Comparative forms are adjective and adverb forms used to compare two things (e.g., “faster,” “quicker,” “more rapid,” “more quickly”). Superlative forms are used in comparisons involving three or more things (e.g., “fastest,” “quickest,” “most rapid,” “most quickly”). Errors in comparative form (CF) and errors in comparative degree (CD) occur when these forms are confused or formed improperly:

Of all the members of the Justice League, Superman has the worse hygiene.

Of all the members of the Justice League, Superman has the worst hygiene.

The first sentence above is an example of an error in comparative degree; because the comparison involves more than two things, the superlative form worst must be used instead of the comparative form worse.

Yoda is the powerfullest Jedi.

Yoda is the most powerful Jedi.

The word powerfullest is an example of an error in comparative form; because powerful has three syllables, the adverb most should be used to express the superlative instead of the suffix -est.

Adjectives and Adverbs

Adjectives describe things; they modify nouns and pronouns. Adverbs describe actions or states; they modify verbs, adjectives, and other adverbs. A common error is confusion of adjective and adverb (A/AC)—using an adjective like an adverb or vice versa:

Tony Parker drove so quick to the basket that his defender was helpless to stop him.

Tony Parker drove so quickly to the basket that his defender was helpless to stop him.

In the example above, the modifier quick describes how Tony drove; it modifies a verb. Therefore, the adverb quickly must be used instead of the adjective quick.

See my Parts of Speech page for more information.

Verbs: Tense and Aspect

Tense refers to the characteristic of verbs that indicates a past, present, or future action or state. Aspect is the characteristic of verbs that indicates how that action or state extends over time (e.g., that it is ongoing or how it is related in time to another state or action). Errors in verb tense (VT) occur when tense or aspect is inconsistent, illogical, or improperly formed:

After Captain Marvel received Nick Fury’s interstellar text message, she is coming back to Earth.

After Captain Marvel received Nick Fury’s interstellar text message, she came back to Earth.

In the example above, it is awkward to combine the past tense received and the present progressive tense is coming. A sequence of two actions in the past is more logical, so the past tense came should be used instead.

See my Verbs page for more information.

Verb Form

English verbs have a number of different forms, such as the present tense form and the past participle form. Errors in verb form (VF) occur when these forms are used or formed incorrectly:

“Yesterday I seen the transit of Mercury across the sun,” Jimbob said.

“Yesterday I saw the transit of Mercury across the sun,” Jimbob said.

Since the tense of the sentence above is simple past (there is no helping verb, and the action is limited to the past), Jimbob should use the past tense form saw instead of the past participle seen.

See my Verbs page for more information.

Use of the Passive Voice

Most English sentences are written in the active voice, meaning that the subject is the agent or doer of the action. In passive voice sentences, the subject is not the doer of the action; it receives or is affected by the action. Although the passive voice plays an important role in English, it is sometimes used in awkward or inappropriate ways. Errors also occur when the passive voice is improperly formed; a “to be” helping verb must be combined with the past participle form of the main verb (e.g., “are written,” “is affected,” “is used” from this paragraph) to form the passive voice. These problems can be identified with the acronym PV.

Batman wanted to play a prank, so Superman’s Cheerios were replaced with Krypton-O’s.

Batman wanted to play a prank, so he replaced Superman’s Cheerios with Krypton-O’s.

In the first sentence above, the passive verb “were replaced” is awkward and confusing because it does not name the doer of the action (which logically should be Batman) and because it is not parallel with the first clause, which is in the active voice (“Batman wanted”). There is no good reason to use the passive voice in this case, so it should be replaced with the active voice “he replaced.”

Note that in the introductory paragraph at the beginning of this section, I chose to use the passive voice several times for two reasons: I was discussing abstract, general actions without a specific agent, and I wanted to provide examples of the passive voice.

See my Verbs page for more information.

Modification and Word Order

In grammatical terms, modification essentially means description. When we form sentences that include a modifier (e.g., an adjective, adverb, or adverbial phrase), we must make it clear exactly what that modifier is describing. Errors occur when the structure of the sentence creates an unclear or illogical relationship between modifiers and what they modify. These errors are generally called misplaced modifiers (MM) or dangling modifiers (DM); when the dangling modifier is a participle, they are called dangling participles (DP).

Hissing loudly, Katana’s paw dealt the vicious roach a deadly blow.

Hissing loudly, Katana dealt the vicious roach a deadly blow with her paw.

The first sentence above has a dangling participle: because the participial phrase “hissing loudly” comes right before “Katana’s paw,” the sentence makes it sound as though the paw is hissing. The sentence must be reworded so that “hissing loudly” is clearly modifying Katana.

Only Vamaria eats Acme Ultra Turtle Superfood Sticks®; she refuses to touch any other food.

Vamaria eats only Acme Ultra Turtle Superfood Sticks®; she refuses to touch any other food.

The placement of only in the first sentence above makes it sound as though only Vamaria, and no other turtle, eats Acme Ultra Turtle Superfood Sticks. The second part of the sentence shows that the first part is intended to suggest that she eats only that kind of food, not any other kind. To make the meaning clear, only must be placed closer to what it actually modifies.

Forming Complete Sentences

Complete sentences require an independent clause: a group of words with a subject and verb that expresses a complete thought. When a group of words lacks one or more of these elements, it is called a fragment (F), and it cannot stand alone as a sentence.

Whenever Aquaman ate a tuna sandwich.

Aquaman ate a tuna sandwich.
Whenever Aquaman ate a tuna sandwich, he felt guilty.

The first sentence above has a subject (Aquaman) and a verb (ate), but it is a fragment because it does not express a complete thought; the subordinating conjunction whenever makes us expect more information to follow it. This kind of fragment can be fixed by removing the subordinating conjunction or by adding an independent clause to complete the thought.

See my Sentence Analysis page for more information.

Connecting Clauses and Sentences

When two independent clauses are joined into one sentence, they are often connected in one of two ways: with a comma and a coordinating conjunction (a “FANBOYS” conjunction) or with a semicolon. A conjunctive adverb like however or therefore along with a semicolon can clarify the logical relationship between the two clauses: 

Aquaman loved the beautiful creatures of the sea, but he also loved tuna sandwiches.
Aquaman loved the beautiful creatures of the sea; he also loved tuna sandwiches.
Aquaman loved the beautiful creatures of the sea; however, he also loved tuna sandwiches.

fused sentence (FS) occurs when nothing is used to connect two independent clauses, and they are simply strung together:

Aquaman loved the beautiful creatures of the sea he also loved tuna sandwiches.

run-on sentence (RS) occurs when only a coordinating conjunction (in this case, but) is used to connect two independent clauses:

Aquaman loved the beautiful creatures of the sea but he also loved tuna sandwiches.

comma splice (CS) occurs when only a comma is used to connect two independent clauses:

Aquaman loved the beautiful creatures of the sea, he also loved tuna sandwiches.

Often, the best way to fix these problems often involves using a subordinating conjunction to make one of the clauses dependent (subordinate) instead of independent. A subordinating conjunction often makes the logical relationship between the clauses clearer:

Although Aquaman loved the beautiful creatures of the sea, he also loved tuna sandwiches.

Other errors in coordination (CE) and errors in subordination (SE) occur when clauses are connected in a mechanically correct but logically unclear or incorrect way:

Aquaman loved the beautiful creatures of the sea, so he also loved tuna sandwiches.

Aquaman loved the beautiful creatures of the sea, but he also loved tuna sandwiches.

The first sentence above contains the required comma and coordinating conjunction, but the logical connection between the two clauses is unclear because the conjunction so expresses cause and effect instead of contrast.

See my Sentence Analysis and Constructing and Connecting Complete Sentences pages for more information.

Diction

Diction simply means “word choice” and is an important component of writing style. It is also one aspect of usage—conventions about how specific words are used by native speakers. Errors in diction (D) occur when a word is misused, often because it is confused with a similar word.

With a dry “Well, we all know how much Superman loves his cheesy snacks,” Wonder Woman made an illusion to the Great Cheeto Catastrophe of 2005.

With a dry “Well, we all know how much Superman loves his cheesy snacks,” Wonder Woman made an allusion to the Great Cheeto Catastrophe of 2005.

In the first sentence above, the word illusion (“something that gives a misleading impression of reality”) is confused with the word allusion (“a reference to something”).

See my Usage page for more information.

Idiom

When we think of idioms, we usually think of colorful figurative expressions like “to blow your mind.” In a broader sense, idioms include any set expression that is used in a certain way. Idiom is another aspect of usage. Errors in idiom (I) often result from using a nonstandard preposition with a specific noun, verb, or adjective.

Hobbits are obsessed to food, gardening, and ale.

Hobbits are obsessed with food, gardening, and ale.

In idiomatically standard English, the participle obsessed requires the preposition with; convention dictates that it should not be used with other prepositions like to.

See my Usage page for more information.

Double Negatives

A double negative (DN) is the use of two or more negative expressions to express the same negation. These expressions include words that emphasize a lack or small amount, such as barelyhardly, and scarcely, in addition to the more obvious no, not, nevernone, etc. In colloquial English, double negatives have been commonly used for centuries to express a negative meaning. In standard English, however, they should be avoided because they cancel each other out, just as two negative numbers do when multiplied.

“I can’t hardly imagine showing up for a party without a bag of pork rinds and a bottle of 1973 Chateau Montelena Chardonnay,” said Skeeter.

“I can’t imagine showing up for a party without a bag of pork rinds and a bottle of 1973 Chateau Montelena Chardonnay,” said Skeeter.
“I can hardly imagine showing up for a party without a bag of pork rinds and a bottle of 1973 Chateau Montelena Chardonnay,” said Skeeter.

Logically speaking, the negative expressions not and hardly in the first sentence above cancel each other out. In this case, either one can be eliminated, though the resulting meanings are different: “can’t imagine” implies an absolute negative meaning, while “can hardly imagine” allows for a small possibility.

Wordiness and Redundancy

Wordiness (W) is the use of more words than necessary to express one’s meaning. Redundancy (R), a specific form of wordiness, is the needless repetition of the same idea multiple times. In most contexts, wordiness and redundancy are stylistic weaknesses that should be avoided.

Our kitten Katana displays many typical feline or cat-like characteristics and qualities, like an obsession with assassinating the elusive red dot of our laser pointer.

Our kitten Katana displays many typical feline characteristics, like an obsession with assassinating the elusive red dot of our laser pointer.

In the first sentence above, the words cat-like and qualities add nothing to the meaning of the sentence, so they should be eliminated to make the sentence tighter and more forceful.

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© 2019 C. Brantley Collins, Jr.